Simultaneous Desulfurization And Denitrification Of Sintering Gas By Using Photo-Fe^ⅡEDTA-Na₂C₂O₄

Sintering flue gas contains large amounts of SO₂ and NOx,causes a lot of environmental pollution,which seriously affects the human health.At present,the industrial technology that focuses on the application of a separate desulfurization or denitration,it has many limitations.Our group,in the earlier stage,studied the wet ammonia sintering flue gas desulfurization systems by Fe^ⅡEDTA,through simultaneous desulfurization and denitrification.Fenton-like reaction and Fenton reaction is widely used in industry for wastewater treatment,Our group has studied the absorption of SO₂ and NO in combination by Fe^ⅡEDTA,and we have achieved some desulfurization and denitration effects.Combined with those results,Photo-Fe^ⅡEDTA-Na₂C₂O₄ was used,absorbing sulfur dioxide and nitric oxide in the simulated sintering flue gas.According to results,the reaction mechanism of Photo-Fe^ⅡEDTA-Na₂C₂O₄ desulfurization and denitrification systems has been confirmed,and also the absorption of SO₂ and NO have been tested.The experiment studied the absorption of NO by the effect of initial pH value,temperature,concentration of Na₂C₂O₄,oxygen and Vis-light.we also studied the effect of simultaneous desulfuration and denitration by Photo-Fe^ⅡEDTA-Na₂C₂O₄ solution.Finally we found the suitable process conditions in Photo-Fe^ⅡEDTA-Na₂C₂O₄ composite absorbent for the absortion of SO₂ and NO.Under anaerobic conditions,when the Photo-Fe^ⅡEDTA-Na₂C₂O₄ system indendently absorbs NO,and the concentration of Fe^ⅡEDTA is 0.03mol/L,Na₂C₂O₄ concentration is 0.03mol/L,0.06mol/L,0.09mol/L,that means the molar ratio between Fe ^ⅡEDTA and Na₂C₂O₄ is from 1: 1 to 1: 3,when the composite absorbent solution absorbing temperature was 50℃,and the initial pH value is 5.5,6.3 and 7.6,the independent denitration by Photo-Fe^ⅡEDTA-Na₂C₂O₄ is better.Simultaneous desulfurization and denitrification in Photo-Fe^ⅡEDTA-Na₂C₂O₄ systems,the concentration of Fe^ⅡEDTA is 0.03mol/L,Na₂C₂O₄ is 0.06mol/L and 0.09mol/L,which means the molar ratio between Fe^ⅡEDTA and Na₂C₂O₄ is 1: 2 and 1: 3,when the initial pH is 5.4,6.6 and 7.5 and its temperature is of 40 ℃ and 50 ℃,the composite absorbing solution absorbs NO better,the maximum denitration rate can be up to 74%,and when the denitration rate dropped to 40%,photocatalytic composite absorbent solution can make its rate increase,appears in the photocatalytic iron oxalate complexing agent for Fe ^ⅡEDTA certain recycling absorption.The optimum conditionsfor complex absorption solution to absorb SO₂ as: when Fe^ⅡEDTA concentration is0.01mol/L,Na₂C₂O₄ concentration is 0.01mol/L and 0.03mol/L,that means the molar ratio between Fe^ⅡEDTA and Na₂C₂O₄ is 1: 1 and 1: 3,and the composite absorption solution temperature is 40 ℃ and 50℃,initial pH value of the composite absorbent is5.3,6.3 and 7.7,the maximum rate of desulfurization can reach99%,and the desulfurization rate can be maintained at above 90%.And when the desulfurization rate decreased,the photocatalytic composite can promote the absorption of SO₂ by composite absorbing solution.Under the conditions of the oxygen content of 12%,Photo-Fe^ⅡEDTA-Na₂C₂O₄ system for NO absorption increased significantly after the start of illumination,and it appears the photocatalytic Fe^ⅡEDTA-Na₂C₂O₄ solution has a regeneration of recycle absorption for Fe^ⅡEDTA.When indenpent denitrification in Photo-Fe^ⅡEDTA-Na₂C₂O₄ system,the concentration of Fe^ⅡEDTA is 0.03mol/L,Na₂C₂O₄ concentration is 0.06mol/L,0.09mol/L,which means Fe ^ⅡEDTA and Na₂C₂O₄ molar ratio is 1: 2 and 1: 3,composite absorbent absorbing solution temperature is 60 ℃,initial pH value are 5.2,6.3,7.7,Photo-Fe ^ⅡEDTA-Na₂C₂O₄ systems indenpent denitration shows better results.Photo-Fe^ⅡEDTA-Na₂C₂O₄ systems simultaneous desulfurization and denitrification,the concentration of Fe ^ⅡEDTA is0.03mol/L,Na₂C₂O₄ is 0.06mol/L,0.09mol/L,which means Fe^ⅡEDTA and Na₂C₂O₄ molar ratio of 1: 2 and 1: 3,the composite absorbent solution temperature are 50℃and 60℃,initial pH value are 6.3 and 7.2,Simultaneous desulfurization and denitrification,the composite absorbing solution shows better absorption of NO.Ion chromatography analysis showed that: the solution contain NO_<sup>3-and SO₄^2-in the product that Photo-Fe^ⅡEDTA-Na₂C₂O₄ absorbing NO and SO₂,while Brown-Ring test also confirms the presence of NO_<sup>3-.NO and SO₂ can be absorbed into the liquid phase by Photo-Fe ^ⅡEDTA-Na₂C₂O₄ and the photocatalytic oxidation the NO and SO₂ in the liquid phase.